This application claims priority of German patent application 199 17 242.0, Apr. 16, 1999.
The present invention relates to a bobbin plate rotatable with a bobbin tube and provided with structure for the formation of a thread reserve winding, also comprising a centering collar which engages in the inside of the bobbin tube, a front-sided bearing surface for the bobbin tube, and thread catching slits which extend inwards from the periphery of the bobbin plate in a direction opposite to the rotational direction of the bobbin plate.
A bobbin plate of this type is prior art in U.S. Pat. No. 4,687,148. In the case of such bobbin plates the centering collar has a slightly smaller diameter than the inside of the bobbin tube due to the necessary clearance when placing on the bobbin tube. This results in the bobbin plate running at a higher speed than the bobbin tube during winding of the thread when the bobbin tube is disposed with a certain pressure load on a drive roller. The known bobbin plate utilizes this in that by means of this relative motion, the thread caught in the thread catching slit is taken along and pulled even deeper into the thread catching slit, until it reaches the inside of the bobbin tube. The aim is to avoid a tensile load on the thread end which has a loosening effect on the thread reserve winding.
It is an object of the present invention to ensure the thread reserve winding even when the thread end is not pulled into the inside of the bobbin tube.
This object has been achieved in accordance with the present invention in that the bobbin plate comprises a base body supported in a rotatable way and a resilient nipping ring which can be pressed on its front side by means of the bobbin tube onto the base body, and in that the base body as well as the nipping ring are each provided with thread catching slits, whereby the thread catching slits of the base body and the thread catching slits of the nipping ring are only identical in the peripheral area of the bobbin plate, whereas further inwards, the thread catching slits of the nipping ring are more inclined in radial direction and extend nearer to the centering collar of the base body, and in that the bearing surface located on the nipping ring has a roughness which prevents a relative motion between the bobbin plate and the bobbin tube.
In preferred embodiments of the present invention, each respective slit base of the thread catching slits located in the base body are covered over by the nipping ring in a resilient way, and in reverse, each respective slit base of the thread catching slits located in the nipping ring are covered over by the base body. After being caught, the thread is pulled into the thread catching slit located in the nipping ring right down to the slit base, and thus is held clamped between the base body and the nipping ring. The non-occurring relative motion between bobbin plate and bobbin tube prevents the clamped thread from leaving the clamping point again while the bobbin tube is rotating. This causes a thread reserve winding to be formed at the edge of the bobbin tube which is sufficiently taut.
In preferred embodiments of the present invention it is provided that the base body is provided with a peripheral groove forming two disc-like edge flanges, and that the edge flanges are provided with identical thread catching slits. The base of the peripheral groove lies deeper than the slit base of the thread catching slits located in the edge flanges, so that there is a certain distance between the caught thread and groove base. This distance is utilized in that the caught thread, after it is clamped between the nipping ring and the base body, is cut lightly between the two edge flanges by means of placing a cutting device thereto. The superfluous thread end is then advantageously suctioned off.
It is favorable when the edge flange facing the nipping ring is slightly conical or convex in form on its front side which is disposed on the nipping ring. This causes the nipping ring, after a bobbin tube has been applied, to take its bearing successively from the inside outwards, the nipping ring then releasing the clamping again after the bobbin tube has been removed, so that the thread end of the thread reserve winding is free again for further use after the bobbin tube has been removed.
For this purpose of the present invention, the edge flange facing the nipping ring can have a smaller outer diameter than the other edge flange. This results in the thread to be caught extending slightly inclined right from the start, so that it can be more easily clamped.
These and further objects, features and advantages of the present invention will become more readily apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings.